Resolved -
This incident has been resolved.
Nov 19, 11:52 CET
Monitoring -
Between November 19, 2025, 05:59:18 UTC and November 19, 2025, 07:41:36 UTC, some clients with rerouting enabled experienced Non-Delivery Reports (NDRs) or were unable to send emails due to a Spamhaus (Microsoft’s default spam service provider) block affecting our US IP address.
Our US IP address (US Data Center) was temporarily blocked by Spamhaus, which is used by Microsoft as its default spam filtering service. During this period, one of our rerouting servers became overloaded with requests, resulting in email delivery delays and NDRs for affected clients.
We do not have direct control over this service, however we have been actively working with both Microsoft and Spamhaus to prevent such issues. Despite these ongoing efforts, the block was imposed again.
Our rerouting tester service triggered an alarm, allowing us to quickly identify the issue and request immediate removal from the blocklist. The IP was successfully removed from the Spamhaus blocklist at 07:41:36 UTC, and normal mail flow has since been fully restored.
We are currently communicating with SpamHaus regarding these incidents, but we have not had any success so far.
We recommend that clients resend any affected emails that may not have been delivered during the disruption window.
Recommended Solution: Switch to the Xink 365 Add-in
To avoid similar disruptions in the future, we strongly recommend switching to the Xink 365 Add-in, which does not rely on email routing or Spamhaus. With the add-in:
✅ No reliance on email servers – signatures are applied directly in Outlook before sending.
✅ No risk of email filtering issues – no interaction with external spam blacklists.
✅ Instant updates – signatures are applied automatically without waiting for mail flow rules.
Most of our clients have already switched and eliminated email delivery risks altogether.
Our team can assist with the transition to ensure a seamless experience.
We strongly encourage you to consider the 365 Add-in for a more reliable and future-proof email signature solution.
Nov 19, 10:04 CET